We have chosen to investigate in depth the following problems: a) The mechanism of action of immunological adjuvants and the search for the most appropriate agents and experimental procedures to enhance cellular immunity and simultaneously depress antibody synthesis, which is a crucial goal to achieve effective cancer immunotherapy. b) The mechanism of rejection of antigenic malignant tissue in vivo and of destruction of individual tumor cells by immune reactions. (The role of thymus-derived cytolytic lymphocytes in these phenomena, the contribution of macrophages to these immune phenomena and to the development of immunity against cancer antigens will be investigated.) c) The distribution of normal surface components of the membranes of malignant cells will be studied as well as the identification of new markers, which are characteristic of the malignant process. d) The relationship of tumor specific transplantation antigens to histocompatibility antigens of the major histocompatibility complex will be investigated both serologically and biochemically. e) An effort will be made to ascertain if histocompatibility linked immune response genes control immunity to TSTA of malignant cells. BIBLIOGRAPHIC REFERENCES: Williams, R. M., Germain, R. N. and Benacerraf, B. Specific and non-specific anti-tumor immunity. I. Description of an in vitro assay based on inhibition of DNA synthesis (IDS) in tumor cells. J. Nat. Cancer Inst. 54:697, 1975. Germain, R. N., Williams, R. M. and Benacerraf, B. Specific and non-specific anti-tumor immunity. II. Macrophage-mediated non-specific effector activity induced by BCG and similar agents. J. Nat. Cancer Inst. 54:709, 1975.